Sorbent canisters, also referred to as sorbent cartridges, perform various absorbing or adsorbing functions for regulating the gas or vapor content of confined environments, such as product packaging. For example, sorbent canisters, such as disclosed in U.S. Pat. Nos. 4,093,105, 4,772,300, and 5,503,662, have been inserted into pharmaceutical packaging, such as pill bottles, to lessen contamination or deterioration of the pharmaceuticals by exposure to moisture or oxygen.
Generally, the canisters have a hollow moisture-impeding plastic cylindrical body and separate porous end caps, and the canisters are filled with granular sorbent of various types for adsorbing moisture or absorbing gases from pharmaceutical containers or other forms of packaging. For example, the canister disclosed in U.S. Pat. No. 4,772,300 features web-bonded polyethylene end caps secured to the ends of a polyethylene body by means of ultrasonic welding. Other such sorbent canisters include the canisters disclosed in U.S. Pat. Nos. 4,093,105 and 5,503,662, which are also arranged for insertion into pharmaceutical containers for the purpose of preventing deterioration of their pharmaceutical contents from moisture. In addition to protecting pharmaceuticals, certain other materials, such as pills, diagnostic test strips, and certain granular substances, which are packed in containers, have similarly benefited from the presence of a material-treating substance to adsorb moisture or absorb oxygen or odors in order to preserve the integrity of those materials.
The sorbent canisters are typically inserted into pharmaceutical bottles or other containers, whose other contents require some form of environmental regulation, by dispensing mechanisms associated with high-speed filling operations. Although the typical sorbent canisters are manufactured to meet dimensional tolerances set for use with the canister dispensing mechanisms, edges formed between the porous end caps and the hollow moisture-impeding plastic cylindrical bodies can sometimes interfere with the dispensing operations.
During known canister fabricating operations, such as disclosed in U.S. Pat. No. 5,942,060, the porous end caps are fused by vibratory welding energy or by heat sealing to the hollow cylindrical bodies and are subsequently trimmed to remove excess material beyond the fusion sites. However, normal dimensional and processing variations within the specified tolerances can leave irregular edges or overhangs that can interfere with the dispensing operations. For example, the irregular edges or overhangs can cause the sorbent canisters to hang up or bind to conveyance structures within the dispensing mechanisms.